Elastic film laminates are used in the manufacture of many goods. In particular, elastic film laminates are used in the manufacture of absorbent articles, such as diapers, training pants adult incontinent articles, and similar articles. The elastic film laminates may be used, for example, as the waist band, leg cuffs, side tabs, side ears, side panels or as the shell of the article. Elastic film laminates also find use in other articles, such as garments, hats, gowns, coveralls, etc. and are typically used to provide desired fit characteristics to the article.
When a film or laminate is made in roll form, the material travels along a path known as the machine direction (“MD”) beginning where the material is formed or unwound to the point where the finished web is wound on a roll. The machine direction will normally correspond to the longest dimension of the web. The cross direction (“CD”) is a direction generally perpendicular to the machine direction and will typically correspond to the width of the web. A number of elastic films and laminates have been proposed, but the vast majority of such films and laminates are engineered and constructed to provide stretch in the cross direction (“CD”).
Heretofore, the most common form of elastic laminate having stretch in the machine direction have not used film, but instead have employed a laminate of elastic strands, such as strands of LYCRA® brand elastomer. In the manufacture of elastic strand laminates, the strands are placed under tension and adhesively laminated to at least one, and typically two nonwoven fibrous webs. The nonwoven webs provide a cloth like texture to the laminate which is preferred by the consumer, as is known. The elastic strands are then allowed to relax, causing the nonwoven to gather and pucker, resulting in a bulky appearance. In some applications, such as training pants and adult incontinent articles, the bulky appearance is objectionable. In order to make the resulting laminate smoother and less bulky, the number of elastic strands used needs to be increased approximately three-fold. The increased number of elastic strands adds to the cost of the laminate, and also results in significantly more complicated and less robust manufacturing process. The increased number of strands becomes difficult to manage and, if any of the strands would break, the process needs to be stopped for a considerable period of time while the strand(s) are re-threaded into the machine.
Accordingly, there is a need for a smoother, less bulky elastic film laminate that has improved properties and can be manufactured in a robust process.